The present invention relates principally to a method of detecting clogging of an air filter and to a system for ventilation, heating and/or air conditioning of a motor vehicle employing such a method.
It is usual to filter the air brought in by a system for ventilation, heating and/or air-conditioning of a passenger compartment of a motor vehicle by making the air pass through an air filter. Particles, especially dust particles, are retained by the air filter which finally becomes clogged, that is to say that it induces significant losses of pressure head reducing the throughput of air passing through the filter, and thus lowers the performance of the ventilation system. The clogging of the filter depends on the size and on the quantity of particles deposited on this filter. Hence, the rapidity of the clogging depends, in very large part, on the conditions of use and especially on the quantity of dust in the air at the time when the heating, ventilation and/or air conditioning system is used.
It is therefore desirable to be able to detect the state of clogging.
Consequently one object of the present invention is to offer a method of detecting filter clogging which is easy to implement.
It is also an object of the present invention to offer a method of detecting filter clogging avoiding false alarms.
It is also an object of the present invention to offer a method of detecting filter clogging employing few special-purpose electronic components.
It is also an object of the present invention to offer a reliable method of detecting filter clogging.
According to a first aspect of the present invention there is provided a method of measuring clogging of an air filter of a system for ventilation, air conditioning, and/or heating of a passenger compartment of a motor vehicle, the method comprising:
a) starting up an air-pumping device including an electric motor driving an air-driving rotating aerodynamic component;
b) measuring a characteristic value of the electric motor driving at least one rotating aerodynamic component for driving the air passing through the filter the clogging of which is being measured, in order to obtain a measurement value;
c) comparing the measurement value with at least one calibration value in order to deduce therefrom a measure of the clogging of the filter.
The method of the present invention may employ the measurement of the strength of the current drawn by an electric drive motor of the air-circulation blower in the system for ventilation, air-conditioning and/or heating of the passenger compartment of a motor vehicle. For example, during a first step, a calibration is carried out. This calibration may be a measurement taken with a new filter. In a case in which the recirculated air is not filtered, it is possible to carry out an acquisition of a calibration value, for example by acquisition of a calibration current ie of the electric motor corresponding advantageously to the ventilation of the passenger compartment of the vehicle by recirculation of the air taken in from this passenger compartment without filtering.
For a measured current i of less than the calibration current ie multiplied by a constant coefficient of less than 1, taking the various corrections into account as appropriate, the filter is considered to be clogged and an alarm is triggered, for example in the form of the display of a light signal.
According to a second aspect the invention provides an installation for ventilation, air conditioning and/or heating of the passenger compartment of a motor vehicle employing the method of the first aspect, the installation including an air filter, air-pumping means including an electric motor driving a rotating aerodynamic component for driving the air, means for measuring a characteristic value of an electric motor driving at least one rotating aerodynamic component for driving the air passing through the said filter in order to obtain a measured value, and means for comparison with a calibration value in order to generate a clogging indication such as an alarm.
The said comparison can be carried out by the computer of the air-conditioning system. The installation may include a means of obtaining the calibration value by measurement of a characteristic value of the electric motor driving at least one rotating aerodynamic component for driving air not passing through the filter, for example recirculated air.